ABSTRACT
Since discovery of the microscope in the 17th century by Dutch tradesmanturned-scientist Antony van Leeuwenhoek (see Fig. 2.1), people started to look in great detail into phenomena that are taking place in tiny objects such as drops of water, leaves, insects, plants, soil, etc. It was realized then that processes in the microscopic world seem to be very complex and chaotic, and that biological systems are surprisingly dynamic. It was the beginning of a long quest for understanding mechanisms that generate forces and motion in living organisms. People were curious to explain these fascinating dynamic properties in cells. It became clear that the motion is closely associated with life since dead organisms do not move, although the source of this dynamic behavior was not understood.
